This invention relates generally to polymerization initiators and more particularly to peroxydicarbonate compositions useful in the polymerization of ethylenically unsaturated monomers, especially vinyl chloride and diethylene glycol bis (allyl carbonate), and an improved polymerization process.
The utility of peroxydicarbonate compounds for initiation of polymerization reactions has been known for a substantially long period of time. One may refer to, for example, U.S. Pat. No. 2,370,588 which discloses generally a class of peroxydicarbonate compounds useful as initiators. One may also refer to U.S. Pat. No. 3,799,916 which relates to peroxydicarbonates including peroxydicarbonates which are asymmetrical in nature, containing both an ethyl or ethenyl group and a tertiary-butyl group. However, no working example in the patent actually refers to the preparation of such an asymmetrical peroxydicarbonate.
Peroxydicarbonates, particularly diisopropyl peroxydicarbonate, have become important initiators especially with respect to the polymerization of vinyl chloride to form polyvinyl chloride and the polymerization of diethylene glycol bis (allyl carbonate), to form a polymer which is customarily known in the trade as CR-39, which is suitable for use in making plastic lenses for eye glasses. Problems associated with diisopropyl peroxydicarbonate include the fact that it is a solid material, rendering it difficult to handle, and the fact that it is unstable, requiring storage at -18.degree. C.
There has, therefore, existed a need for initiator compositions to replace diisopropyl peroxydicarbonate, preferably having better physical properties and/or better safety characteristics.